Arc device



J. FORCE ARCVDEVICE.

Filed March 1, 1922 Fig l.

Inventor: Jonathan Force,

H is Attorn e3 mama Nov. 23,1926.

UNITED STATES PATENT OFFICE.

JONATHAN FORCE, OF LIVINGSTON, NEW JERSEY. ASSIGNOB TO GENE EAL ELECTRIC COMPANY, A. GOBIORATIONOF NEW YORK.

ARC DEVICE.

Application filed March 1, 1922. Serial 110.5),276.

The present invention relates to devices in which an arc is operated in a gaseous atmosphere between electrodes of which either the negative electrode alone, or both electrodes, operate at incandescence.

It is the object of my invention to improve the operation and life of an incandescent electrode device. In accordance with one of the features of my invention, the trouble which is'sometimes experienced due to the are playing between the leading-in conductors during starting is obviated. As these conductors are not adapted to serve as electrodes they are sometimes fused and in many cases the seals are cracked by the are traveling to the point of entry of the conductors into the bulb. Other features of my invention, for example, the reduction of flickering and the suppression of electrode disintegration, are hereinafter described.

I have discovered that when a section of the current conveying conductor adjacent the cathode is associated with a material having a higher electron emissivity than the rest of the conductor that then the arc will be confined to the electrodes.

The accompanying drawing illustrates in Fig. 1 one embodiment of my invention in longitudinal section; Fig. 2 illustrates a modification; and Figs. 3, 4 and 5 illustrate different starting devices applied to lamps embodying myinvention.

The device shown in Fig. 1 is particularly intended to operate as a lamp and therefore, the electrodes 1, 2 are of substantially equal size, both electrodes consisting of a refractory metal. preferably tungsten, and both ordinarily being operated at bright incandescence. These electrodes are carried by conductors, 3. 4, which may also consist of tungsten, and are sealed into the envelope 5. which consists of glass having substantially the same coefiicient ofexpansion as tungsten. Theti s 6, 7 of the conductors 3, 4 are bent at an angle to the rest of the conductors and toward each other so as to make the gap between the ilixtaposed electrodes 1, 2 shorter than the distance between the conductors 3, 4. The envelope 5 contains a gaseous or gasifiable material which at the operating temperature of the lamp has a pressure high enough to cause an electrical discharge between the electrodes 1, 2 to become concentrated and assume the characteristics of an electric arc, the energy of the discharge being enough to heat the electrodes to incandescence. For-example, the bulb may contain a quantity of mercury 8 and a filling of an inert gas such as argon, or'nitrogen. The wires 3, 4 are insulated from the mercury by insulating coatings 9, 10 of glass or the like.

The container or bulb 5 ordinarily is elongated to provide a condensing space above the arc.v Preferably there is provided a separate chamber 11 connected to the main condensing chamber 13 by a constricted orifice 12 which is in line with the trajectory of the blast of mercury vapor emanating from the are between the electrodes 1, 2. .The mercury vapor blast enters this auxiliary chamber 11, where the vapor pressure is determined by the temperature of the walls of the auxiliary chamber. This chamber therefore, functions to regulate the gaseous pressure about the electrodes.

In order to prevent electrode disintegration during the operation of the arc, the parts of the device must be arranged and proportioned to enable the arc to operate with a voltage consumption below a limiting value depending on the character of the device, particularly' the length of the are. One of the conditions controlling the volt-- age drop between the electrodes is the pressure of the gas or vapor in which the arc operates. By the addition of the chamber 11, the pressure may be maintained at a lower value. Consequently the arc 'willbe stabilized at a lower voltage and the disintegration of the electrodes will be largely suppressed.

The auxiliary chamber should be propor- The constriction or throat 12 should- No. 1,578,973; issuedMarch 30, 1926, I have made claims on ,the bulb structure shown in Fig. 1.

At the end of the straight portions of the conductors 3, 4 and adjacent the electrodes 1, 2 are located particles 14, ot a material having a higher electron emisslvity than the lead wires. For example these beads may consist of tungsten containing thoria, or of metallic thorium, or an alloy of thorium. I

prefer to use tungsten containing about 5% thoria. This material may be prepared as described in Coolidge Patent 1,082,933. The thoriated tungsten mass may be welded as a head, or a short length of wire to the lead wires.

In some cases a short section of the lead wires, say, one-half inch, adjacent the electrode stems 6, 7 may consist of thoriated tungsten. Such a construction is shown in Fig. 2 which illustrates a somewhat modified arc device in which the lead wires 3, 4, project downwardly through a condensing chamber 13' instead of projecting through the mercury. The sections 16, 17 of the lead wires consist of thoriated tungsten.

In the devices illustrated in Figs. 1 and 2 both electrode leads are provided with thoriated tungsten for localizing the arc to permit operation with alternating current. When an incandescent arc device is intended for operation with direct current, the cathode conductor only need be provided with a material of high electron emissivity.

When a device constructed in accordance with my invention is placed into operation, for example, by producing a high potential discharge between the electrodes 1, 2, the arc starts from the thoriated particles, 14, 15, remains there for a short time until the elec trodes, 1, 2 become heated, and then because of the spatial relation of the electrodes to the thoriated particles, the arc will jump to the electrodes where it continues to steadily operate.

When the arc has once been started between the electrodes 1, 2 and therefore, has

heated these electrodes to incandescence, there is little or no tendency for the arc to desert the electrodes, but in the absence of the thoriated masses, the arc would tend to flicker. The high electron emission from the thoriated tungsten counteracts this tendency and promotes a smooth, steady operation of thearc. v

Although the are may be started by a high voltage discharge it is desirable in many cases to start the are by a low-voltage auxiliary discharge. For example, I have illustrated in Fig. 3 an arc device in which two conductors 20, 21 depend from the electrode conductors and dip into the mercury body'8. These conductors 20, 21 are near enough to the gap between the electrodes 1, 2, to ionize the gas in the gap.

The mercury communicates through a. tube 22 with an auxiliary chamber 23 containing a gas at the same pressure, or a proximately so, as the gas in the main b b 5. When current at suitable voltage is impressed upon the conductors 3, 4 the conductors .20, 21 become incandescent and the arc starts between the electrodes. As the gas or vapor pressure builds up in the bulb 5, some of the mercury therein is pushed out through the tube 22 into the bulb 23, thereby breaking the circuit through the conductors 2 0, 21.

In Figs. 4, 5 I have illustrated devices embodying my invention having conductors 24,

25. connected to the electrode conductors 6,

1, 2. A restoration of the bulb to an upright position causes these starting arcs to lengthen and break.

What I desire to secure by Letters Patent of the United States, is

1. A gas ionization device provided with refractory electrodes spaced apart durin starting and having in combination with sai electrodes, a material of higher electron emissivity than said electrodes and associated with said electrodes in such spatial relation that an electric discharge initiated from said material will be transferred to said electrodes.

2. An electrical discharge device comprising'the combination of a container, currentcarrying conductors sealed into said container, electrodes consisting of refractory material supported by said conductors and located adjacent each other with an intervening gap, .and a quantity of thorium material associated with at least one of said conductors in such position relative to the electrode apart a shorter distance than said conductors, I

and a quantity of material ,containin thorium as an elementary constituent app ied to one or more of said conductors at. a region spaced away from' the electrode mounted thereon.

4. An arc device comprising the combination of a container, conductors sealed into,

said container bearing cooperating electrodes, a gas or gasifiable material in said container capable of giving a discharge between said electrodes an arc-like characteristic and a material capable of evolving thorium applied to one of said conductors in such position that an are passing from said material to the cooperating electrode will heat the electrode borne upon the conductor on which said material is applied and will thereby facilitate the starting of an are from said electrode.

5. An arc device comprising the combination of a container, electrodes therein for supporting an arc, current supply conductors for said electrodes and means for increasing the electron emissivity of one of said conductors at a region adjacent to the electrode carried by said conductor, said means being so positioned with respect to the cooperatin electrode that are started by said means will operate between said electrodes.

6. An are device charged with gas at substantial pressure containing electrodes of refractory material, stems fixedly supporting said electrodes out of electrical contact with each other, and a medium capable of becoming the seat of an are more readily than said supporting stems and electrodes mounted in such position on said stems that an are started therefrom will be transferred to said electrodes.

7 An arc device comprising the combination of a bulb, electrodes therein consisting of tungsten, electric conductors therefor, a quantity of thoria associated with said conductors adjacent said electrodes, and a quantity of mercury in said bulb, and means 00- operating with said mercury to start an are between said electrodes.

8. An electric arc lamp comprising a sealed bulb, a gas or gasifiable material therein which will have during operation of said device a substantial pressure, current supply conductors mounted in fixed relation in said bulb. the end portions of said conductors extending toward each other in a plane substantially at right angles to the remaining portion thereof, electrodes of refractory material aflixed to the tips of said conductors, and a quantity of material of higher electron emissivity than said electrodes afiixed to said conductors in the plane of said end portions and spaced away from said electrodes.

In witness whereof, I have hereunto set my hand this 25th day of February 1922.

JONATHAN FORCE. 

